Storage tanks for liquids

A land storage tank arrangement for the storage of fluid media under pressure, comprising an internal-pressure-sustaining insulatable tank of generally rectangular cross-section having a bottom wall, a top wall, two opposite longitudinal side walls and two opposite end walls;

• each of said bottom and top walls consisting of a multiplicity of equal-sized parallel lobes, and each said side wall consisting of one lobe, the side wall lobes also being equal-sized, all said lobes being of part-cylindrical form and being convex outwardly of the tank with the two inwardly-directly longitudinal edges of each lobe joined to a longitudinal edge of a lobe alongside;
• and said end walls consisting of a multiplicity of part spherical end wall elements having the same radius of curvature as said lobes and each joined at its inwardly directed edges to end wall elements alongside and to bottom, top and side wall lobes alongside to unite said bottom, top, side and end walls to one another;
• said insulatable tank further comprising a single series of parallel internal reinforcing plates, each plate extending from the joint between two lobes of the bottom wall to the respective opposite joint between two lobes of the top wall and extending longitudinally to the joints of opposed end wall elements to tie the tank end walls to one another longitudinally;
• said storage tank arrangement further comprising a shallow dyke in which the tank is sited at least partly below ground, said dyke having dyke walls being spaced from the tank by a space filled with a thermal insulating material and an inert gas atmosphere, a substantially flat roof which extends over the tank and is sealed to the dyke walls, and roof support means comprising feet spaced apart on the underside of the roof and sited so as to sit on the joints between adjacent lobes of the top wall or the tank whereby the span or the roof is supported by said insulatable tank, wherein one or more of said internal reinforcing plates is liquid tight so as to divide the tank into separate storage compartments, said space is partitioned at positions corresponding to the liquid tight plates, and a ring of sniffers is located around the tank in each partitioned area, thereby enabling inert gas from each partitioned area to be sampled separately thereby to monitor its associated storage compartment of the tank for leaks.